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Submitted by: Submitted to:Submitted by: Submitted to:Ankit GuptaAnkit Gupta Prof. Shikha Agrawal Prof. Shikha Agrawal0101CS1110130101CS111013 Prof. Rajeev Pandey Prof. Rajeev PandeyCSE-A CSE-A

Voice over IPVoice over IP

Contents Abstract What is VoIP How VoIP works VoIP Architecture Applications

Abstract Voice over Internet Protocol

(VoIP) is a technology that enables one to make and receive phone calls through the Internet instead of using the traditional analogy PSTN (Public Switched Telephone Network) lines.

What is VoIP?

VoIP is packetisation and transport of classic public switched telephone system audio over an IP network.

It allows 2-way voice transmission over broadband connection.

It is also called IP telephony, internet telephony, voice over broadband, broadband telephony.

PSTN vs. INTERNETPSTN

Voice network use circuit switching.

Dedicated path between calling and called party.

Bandwidth reserved in advance.

Cost is based on distance and time.

INTERNET Data network use packet

switching. No dedicated path between

sender and receiver. It acquires and releases

bandwidth, as it needed. Cost is not based on

distance and time.

PBX

Yesterday’s NetworksCircuit Switched Networks (Voice)

CO

PBX

COCO

Packet Switched Networks (Data)Router

RouterRouter

Router

Router

• Separated networks• Separated applications/services

PBX

IP Phone

Converged Network

PSTN

CO

Gateway

RouterRouter

RouterRouter

• Converged network• Separated or integrated applications

PBX

IP Phone

VoIP – How does it work? Converting the voice signal

ADC (analog to digital) DAC (digital to analog)

Voice (source) - - ADC - - - Internet - - - DAC - - Voice (dest)

Transmission of voice traffic in packets

VoIP – How does it work? The 1-2-3s of VoIP

1. Compression – voice is compressed typically with one of the following codecs, G7.11 64k, G7.29AB 8k, G723.1 6.3k

2. Encapsulation – the digitized voice is wrapped in an IP packet

3. Routing – the voice packet is routed thru the network to its final destination

LTS©Telcordia Technologies, Inc. Slide 11

IP Network

Multimedia PC

Multimedia PC

Initially, PC to PC voice calls over the

Internet

VoIP Architecture?

PSTN(DC)

Gateway

PSTN(NY)

Gateway

Public Switched Telephone Network

Gateways allow PCs to also reach phones

…or phones to reach phones

ApplicationsWeb applications such as MSN Messenger, Skype, AOL Messenger, AIM, Apple Chat use this protocol to connect with other users for voice and video connection over the

internet. Most of these applications are free, but can be upgraded for a subscription fee.

VoIP is useful because it is a great way to stay in contact with friends and family using video and voice chat over the internet.

Recently it has been brought to Xbox Live and Playstation (PSN) for chat whilst playing a game.

Games such as Call Of Duty, including many other first person shooting games use this facility so that the game is more realistic and you are able to connect with other players who are playing the same game.

Do Companies Want VoIP?

76% Will!76% Will!

Unsure

4%Not at all

likely

4%Not very

likely

16%

Likely

28%

Very likely

32%

Extremely

likely

16%

Network World asked 500 readers to assess whether they would consider using voice over IP:

Key Business Drivers for LAN-Based Telephony and VoIP

81%81%

59%59%

38%38%

26%26%

0 50 100

Save MoneySave Money

Better Utilization of BandwidthBetter Utilization of Bandwidth

Support MultimediaSupport Multimedia

Improve Network ManagementImprove Network Management

Security Risks As VoIP uses the Internet, for example, it is vulnerable to

the same type as security risks Hacking Denial of service Eavesdropping